Sumptuous, palate-pleasing sushi: who doesn’t love it? There’s plenty to salivate over as this documentary traces the history, art, and technique of sushi-making worldwide, but it’s no empty paean to the briny delicacy. The fate of the Blue Fin Tuna and other prized ocean species hangs in the balance as a result of the rising popularity of sushi as a favorite food in nations including the U.S. and China. Director Hall examines the growing crisis through encounters with sushi chefs and environmental experts including author Casson Trenor, Time Magazine’s 2010 “Hero of the Environment,” and founder of the world’s first sustainable sushi restaurant.